JP2019034616A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize manual steering even if steering intervention is performed by a driver during automatic steering, and to further secure safety at the time of emergency steering by the driver, an electric power steering device having both assist control and steering angle control. I will provide a. SOLUTION: A steering angle control unit that calculates a steering angle control current command value for steering angle control based on at least a steering angle command value and an actual steering angle, and a steering state are determined based on a manual input determination. , A switching determination / gradual change gain generation unit that switches the steering state is provided, and the switching determination / gradual change gain generation unit responds to an error between the estimated steering angle and the actual steering angle estimated based on the steering angle command value. A manual input determination unit including a first determination unit for determining manual input using an error threshold is provided, and a current command value is calculated using at least a rudder angle control current command value. [Selection diagram] FIG. 7

Description

  The present invention relates to an electric power steering apparatus that enables automatic steering by performing assist control and steering angle control on a steering system by drive control of a motor based on a current command value, and in particular by a driver during automatic steering. The present invention relates to an electric power steering apparatus that is safe and can reduce a sense of incongruity even when steering intervention is performed.

  An electric power steering device (EPS) that applies a steering assist force (assist torque) to a steering system of a vehicle by a rotational force of a motor is driven by a transmission mechanism such as a gear or a belt via a speed reduction mechanism. Assist control is performed by applying a steering assist force to the shaft or the rack shaft. Such a conventional electric power steering apparatus performs feedback control of motor current in order to accurately generate assist torque. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). This is done by adjusting the duty of modulation) control.

  A general configuration of the electric power steering apparatus will be described with reference to FIG. 1. A column shaft (steering shaft, handle shaft) 2 of the handle 1 is a reduction gear (worm gear) 3 constituting a reduction mechanism, universal joints 4a and 4b, The pinion rack mechanism 5 and the tie rods 6a and 6b are connected to the steering wheels 8L and 8R via the hub units 7a and 7b. Further, a torsion bar is inserted in the column shaft 2, and a steering angle sensor 14 for detecting the steering angle θ of the steering wheel 1 by a torsion angle of the torsion bar and a torque sensor 10 for detecting the steering torque Tt are provided. A motor 20 that assists the steering force of the handle 1 is connected to the column shaft 2 via the reduction gear 3. The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11. The control unit 30 calculates the current command value of the assist control command based on the steering torque Tt detected by the torque sensor 10 and the vehicle speed V detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the motor 20 is controlled by the voltage control command value Vref.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be acquired from a rotation angle sensor such as a resolver connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that exchanges various types of vehicle information, and the vehicle speed V can also be received from the CAN 40. The control unit 30 can be connected to a non-CAN 41 that exchanges communications, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 30 is mainly composed of a CPU (including an MPU, MCU, etc.). FIG. 2 shows general functions executed by a program inside the CPU.

  The control unit 30 will be described with reference to FIG. 2. The steering torque Tt detected by the torque sensor 10 and the vehicle speed V detected by the vehicle speed sensor 12 (or from the CAN 40) are a current command for calculating a current command value Iref1. The value is input to the value calculation unit 31. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Tt and the vehicle speed V. The current command value Iref1 is input to the current limiter 33 through the adder 32A, and the current command value Irefm whose maximum current is limited is input to the subtractor 32B, and the deviation I (= Irefm) from the fed back motor current Im. -Im) is calculated, and the deviation I is input to a PI (proportional integration) control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is further PWM driven via the inverter 37. The motor current Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B. The inverter 37 is composed of an FET bridge circuit as a semiconductor switching element.

  A rotation angle sensor 21 such as a resolver is connected to the motor 20, and the rotation angle θ is detected and output from the rotation angle sensor 21.

  Further, the compensation signal CM from the compensation signal generation unit 34 is added to the addition unit 32A, and the compensation of the steering system system is performed by the addition of the compensation signal CM, thereby improving the convergence and inertia characteristics. ing. The compensation signal generator 34 adds the self-aligning torque (SAT) 34C and the inertia 34B by the adder 34D, further adds the convergence 34A to the addition result by the adder 34E, and compensates the addition result of the adder 34E. The signal CM is used.

  In recent years, research and development of automatic driving technology for vehicles has been advanced, and proposals have been made to apply an electric power steering device (EPS) in automatic steering. When automatic steering is realized by EPS, a mechanism for assist control executed by conventional EPS and a mechanism for steering angle control for controlling the steering system so that the vehicle travels in a desired direction are independent. It is common to have a configuration in which these outputs can be adjusted. In the steering angle control, position / speed control having excellent performance in response to the steering angle command which is a control target of the steering angle and disturbance suppression against road surface reaction force, etc. is used. PI (proportional integral) control is adopted in (proportional) control and speed control.

  When assist control and rudder angle control are executed independently, and the entire control is performed by switching the command value that is output from both, if the switch is suddenly switched, the command value will fluctuate suddenly and the steering wheel behavior May become unnatural and may make the driver feel uncomfortable. In Japanese Patent Application Laid-Open No. 2004-17881 (Patent Document 1), as a response to this problem, a command from both of the switching between the torque control method (equivalent to assist control) and the rotation angle control method (equivalent to steering angle control) is performed. A value obtained by multiplying each value by a coefficient (automated coefficient and manual coefficient) and adding the result is used as a final command value, and the coefficient is gradually changed to suppress sudden fluctuations in the command value. Moreover, P control is used for position control in the rotation angle control system, and PI control is used for speed control.

  Japanese Patent No. 397008 (Patent Document 2) proposes an automatic steering control device that automatically performs a hand operation in accordance with a set steering angle, and particularly for the purpose of parking assistance. In this device, a torque control mode (equivalent to assist control) and a parking assistance mode (equivalent to steering angle control) can be switched. In the parking assistance mode, control is performed using previously stored parking data. Is going. Then, P control is performed in the position control in the parking assist mode, and PI control is performed in the speed control.

  Japanese Patent No. 3912279 (Patent Document 3) does not directly apply EPS, but when the steering angle control is started by switching to the automatic steering mode, the steering speed (steering angular speed) is gradually increased. This reduces the driver's uncomfortable feeling due to sudden fluctuations in the steering wheel at the start.

JP 2004-17881 A Japanese Patent No. 3917008 Japanese Patent No. 3912279

  However, in Patent Document 1, since the command value for the steering angle control (steering angle control command value) is limited by the coefficient and is output to the final command value during the switching of the method, the final command value is decreased by the limited amount. turn into. Due to this restriction, the actual speed of the motor becomes slower than the command value for the steering angular speed (steering angular speed command value) calculated from the steering angle control command value, so there is a deviation between the steering angular speed command value and the actual speed. Occurs, and the integrated value of I (integral) control in the speed control is accumulated, and a larger steering angle control command value is output from the speed control. As a result, in a state where the coefficient multiplied by the command value for the assist control (assist control command value) is gradually increased, the restriction by the coefficient is relaxed, so that the steering angle control command value increases as the coefficient increases. Therefore, the steering wheel may react excessively with respect to the steering angular velocity command value, and may give the driver a sense of incongruity or discomfort such as a feeling of being caught.

  In Patent Document 1, P control is used for position control and PI control is used for speed control. If there is manual input by the driver during the steering angle control, the steering angle control is the steering angle control command value. Therefore, it is difficult to manually steer until the switching operation from the steering angle control to the assist control is performed. In addition, there is a possibility that a time delay occurs due to the manual input detection or the switching operation, and the steering intervention operation by the driver cannot be sufficiently performed.

  Also in Patent Document 2, rudder angle control using P control for position control and PI control for speed control is performed. When steering angle control is performed in a vehicle, disturbances and load conditions greatly change due to changes in vehicle speed, friction, road reaction force, and the like, so the apparatus must have a control configuration that is resistant to them. However, with only the control configuration of the device described in Patent Document 2, for example, when the road surface reaction force changes or the target steering angle changes quickly, vibration is generated by the natural vibration caused by the spring of the steering wheel mass and the torsion bar. In addition, the driver may feel it uncomfortable or uncomfortable.

  In Patent Document 3, the steering angular speed is gradually increased at the start of the steering angle control. However, when the increase starts, the steering angular speed continues to increase until reaching the upper limit value of the steering angular speed, so that the integral value of the I control accumulates excessively. . As a result, the steering angle control command value becomes an excessive value, and the steering wheel may react excessively with respect to the steering angular speed command value, which may give the driver a sense of incongruity.

  The present invention has been made under the circumstances described above, and an object of the present invention is to realize manual steering even when steering intervention is performed by a driver during automatic steering, and safety during emergency steering by the driver. It is an object to provide an electric power steering apparatus that further ensures assist and is compatible with assist control and steering angle control. In addition, the driver feels uncomfortable and uncomfortable, such as a feeling of being caught when switching from automatic steering to manual steering.

  The present invention relates to an electric power steering apparatus that drives a motor based on a current command value and performs assist control and steering angle control on a steering system by driving control of the motor. A steering angle control unit that calculates a steering angle control current command value for the steering angle control based on the command value and the actual steering angle, a steering state is determined based on manual input determination, and the steering state is switched. A switching determination / gradual change gain generation unit that performs an error with respect to an error between the estimated steering angle estimated based on the steering angle command value and the actual steering angle. This is achieved by including a manual input determination unit including a first determination unit that determines the manual input using a threshold, and calculating the current command value using at least the steering angle control current command value.

  The object of the present invention is to provide the first determination unit having a plurality of error smoothing filters having different characteristics, and smoothing the error by each of the error smoothing filters to obtain a plurality of smoothing errors. By determining the manual input using the error threshold for each of the smoothing errors, or the first determination unit uses a plurality of the error thresholds for at least one of the smoothing errors. The second determination unit further includes a second determination unit that has a plurality of determination results as determination results with manual input, or wherein the manual input determination unit determines the manual input using a torque threshold with respect to a steering torque. Alternatively, the second determination unit has a plurality of torque smoothing filters having different characteristics, and each of the torque smoothing filters smoothes the steering torque to thereby smoothen the plurality of smoothing. By obtaining a rudder torque and determining the manual input for each of the smoothed steering torques using the torque threshold value, or the second determining unit is configured for at least one of the smoothed steering torques. By using a plurality of torque thresholds and having a plurality of determination results as determination results with manual input, or the rudder angle control unit determines a rudder angular velocity command value based on the rudder angle command value and the actual steering angle. A position control unit that computes the position, a position control output variable limiting unit that limits the steering angular speed command value with a limit value 1 set according to the steering state, and outputs a limited steering angular speed command value; A rudder angular speed control unit that calculates the rudder angle control current command value based on the limited rudder angular speed command value and the actual rudder angular speed, or the rudder angle control unit includes the steering torque A steering intervention compensation unit for obtaining a compensation steering angular speed command value for steering intervention compensation according to the rotational speed information and the vehicle speed, and compensating the limit steering angular speed command value using the compensation steering angular speed command value; The steering intervention compensator uses a basic map that is sensitive to vehicle speed to obtain a first speed command value from the steering torque, and a damper gain map that is sensitive to vehicle speed, based on the rotational speed information. A damper calculation unit for obtaining a two-speed command value, and calculating the compensation steering angular speed command value from the first speed command value and the second speed command value, or the damper gain map includes the vehicle speed The speed command value level at which the steering intervention compensation unit performs phase compensation before or after the basic map unit. A phase compensation unit, and obtaining the first speed command value from the steering torque via the basic map unit and the speed command value phase compensation unit; or By providing a proportional gain unit that calculates a rudder angular velocity command value by multiplying a deviation between the command value and the actual steering angle by a proportional gain, or the rudder angular velocity control unit includes the limited rudder angular velocity command value and the By calculating the rudder angle control current command value by IP control using the actual rudder angular velocity, or when the switching determination / gradual gain generating unit changes the operation mode to the assist control mode or the rudder angle control mode. A switching state signal, a steering state determination unit that determines the steering state based on a first determination result of the first determination unit and a second determination result of the second determination unit, and the steering state according to the steering state, A gradual change gain generation unit that generates a gradual change gain that adjusts the control amount of the cyst control and the control amount of the rudder angle control, or the steering state determination unit has the switching signal as the assist control. In the case of the mode, or when the immediately preceding steering state is automatic steering 1 or automatic steering 2 and the first determination result or the second determination result is manual input 3, the steering state is determined to be manual steering. Alternatively, the steering state determination unit may determine that the immediately previous steering state is the manual steering or the automatic steering 2, the switching signal is the steering angle control mode, and the first determination result and When the second determination result indicates no manual input, the gradual gain generating unit determines whether the steering state is the automatic steering 1 or the gradual gain generating unit has a predetermined first An in value is set to the gradual gain, a predetermined second gain value is set to the gradual gain for the manual steering, and the gradual gain is changed when the steering state is changed to the automatic steering 1. When the steering state changes to the manual steering when the steering state is changed to the first gain value, the gradual gain is changed to the second gain value, or the position control output variable limiting unit When the state changes from the automatic steering 1 to the automatic steering 2 or the manual steering, the limit value 1 is changed to the set value 1, or the position control output variable limiting unit When the automatic steering 1 is changed to other than the automatic steering 1, the limit value 1 is changed to a setting value 2 larger than the setting value 1, or the steering angle control unit Change On the other hand, by further comprising a variable rate limiting unit for limiting by the limit value 2 set according to the steering state, or the variable rate limiting unit, the steering state from the automatic steering 1 to the When changing to the automatic steering 2 or the manual steering, the variable rate limiting unit changes the steering state from other than the automatic steering 1 to the automatic steering 1 by changing the limit value 2 to zero. An assist control unit that calculates an assist control current command value for the assist control by transitioning the limit value 2 to a predetermined value, or at least based on a steering torque, and the assist control current This is achieved more effectively by calculating the current command value from the command value and the steering angle control current command value.

  According to the electric power steering apparatus according to the present invention, since the steering state is switched by using the manual input determination, even if there is a steering intervention during automatic steering, it is possible to reduce the sense of incongruity safely. Switching from suppressed automatic steering to manual steering is possible.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control unit (ECU) of an electric power steering apparatus. It is a block diagram which shows the structural example of the whole vehicle system concerning this invention. It is a block diagram which shows the structural example of a switching determination / gradual change gain production | generation part. It is a block diagram which shows the structural example of a manual input determination part. It is a graph which shows the example of a change of the gradual change gain according to a steering state. It is a block diagram which shows the structural example of a steering angle control part and a switching part. It is a characteristic view which shows the example of the limiting value in a steering angle command value variable limiting part. It is an image figure which shows the example of the mode of the manual input determination result at the time of steering intervention generation | occurrence | production by a driver | operator, and the change state of a steering state. It is a block diagram which shows the structural example of a position control part. It is a block diagram which shows the structural example of a steering intervention compensation part. It is a characteristic view which shows the example of a basic map. It is a characteristic view showing an example of a damper gain map. It is a characteristic view which shows the example of the limit value in a speed command value variable limiting part. It is a block diagram which shows the structural example (1st Embodiment) of a steering angular velocity control part. It is a block diagram which shows the structural example of a steering wheel damping part. It is a characteristic view which shows the example of the limiting value in a steering angle control electric current command value limiting part. It is a flowchart which shows the operation example of EPS side ECU. It is a flowchart which shows a part of operation example of a switching determination / gradual change gain production | generation part. It is a flowchart which shows a part of operation example of a switching determination / gradual change gain production | generation part. It is a flowchart which shows a part of operation example (1st Embodiment) of a steering angle control part. It is a flowchart which shows a part of operation example (1st Embodiment) of a steering angle control part. It is a flowchart which shows the operation example of a steering intervention compensation part. It is a block diagram which shows the example of the driver | operator's steering model used by simulation. It is a graph which shows the example of the time response of the target angle in the simulation regarding steering intervention compensation, an actual steering angle, and a steering torque. It is a graph which shows the example of a change of the actual steering angle and steering torque in the simulation regarding steering intervention compensation. It is a graph which shows the simulation result regarding the followability with respect to a steering angle command value. It is a graph which shows the simulation result regarding steering wheel vibration. It is a graph which shows the example of the time response of the target angle and steering wheel input torque in the simulation regarding the rudder angle change by hand release after steering intervention. It is a graph which shows the example of the time change of the limit value in the simulation regarding the rudder angle change by hand release after steering intervention. It is a graph which shows the simulation result regarding the rudder angle change by the release after the steering intervention. It is a graph which shows the example of change (1st Embodiment) of the target rudder angular velocity at the time of steering state transition, a gradual gain, and a limit value. It is a block diagram which shows the example of insertion of a speed command value phase compensation part. It is a block diagram which shows the structural example (2nd Embodiment) of a steering angular velocity control part. It is a block diagram which shows the structural example (3rd Embodiment) of a steering angular velocity control part. It is a graph which shows the change example (4th Embodiment) of the target rudder angular velocity at the time of steering state transfer, a gradual gain, and a limit value.

  The electric power steering apparatus (EPS) according to the present invention performs assist control, which is a function of a conventional EPS, and steering angle control necessary for automatic steering in automatic driving. The assist control and the steering angle control are executed by the assist control unit and the steering angle control unit, respectively, and the current for driving and controlling the motor using the assist control current command value and the steering angle control current command value output from each unit. Calculate the command value. Both steering angle control and assist control are executed in automatic steering (automatic steering state), and assist control is executed in manual steering (manual steering state) in which the driver is involved in steering. Switching between automatic steering and manual steering is generally performed by a switching signal from a control unit (ECU) or the like mounted on the vehicle, but even if steering intervention occurs from the driver during automatic steering, In the present invention, a manual input determination is made based on the error of the estimated steering angle and the actual steering angle so that a quick and smooth transition to manual steering is performed, and switching determination between automatic steering and manual steering is also performed using the determination result. Further, a switching operation is performed. The switching determination is performed by the switching determination / gradual gain generating unit. Further, in order to reduce a sense of incongruity caused by steering intervention during automatic steering, steering intervention compensation can be performed. Specifically, the compensation value (first speed command value) obtained from the steering torque using the basic map and the rotational speed information (for example, the steering angular speed) that is information relating to the rotational motion speed in the steering system using the damper gain map. Etc.) is compensated with a compensation value (compensated steering angular speed command value) calculated from a compensation value (second speed command value) obtained based on the above. In order to prevent a sudden change in the steering angle when the steering wheel is released after the steering intervention by the driver, it is possible to limit the steering angular speed command value according to the steering state.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the entire vehicle system including the electric power steering apparatus according to the present invention will be described.

  FIG. 3 shows a configuration example (first embodiment) of the entire vehicle system according to the present invention. The ECU (hereinafter referred to as “vehicle side ECU”) 100 mounted on the vehicle, the ECU mounted on the EPS ( (Hereinafter referred to as “EPS side ECU”) 200 and plant 400.

  The vehicle-side ECU 100 includes a vehicle state quantity detection unit 110, a switching command unit 120, a target track calculation unit 130, and a vehicle motion control unit 140.

  The vehicle state quantity detection unit 110 outputs data detected from the in-vehicle camera, the distance sensor, the angular velocity sensor, the acceleration sensor, and the like as the vehicle state quantity Cv to the switching command unit 120, the target trajectory calculation unit 130, and the vehicle motion control unit 140. To do.

  The switching command unit 120 inputs a signal Sg for switching the operation mode together with the vehicle state quantity Cv from a button, a switch, or the like provided on a dashboard or the like, and outputs a switching signal SW to the EPS side ECU 200. The operation modes include “assist control mode” and “steering angle control mode”, “assist control mode” is a mode corresponding to manual steering, and “steering angle control mode” is a mode corresponding to automatic steering. Based on the value of the signal Sg indicating the driver's intention, the operation mode is determined in consideration of the value of each data in the vehicle state quantity Cv, and the determined operation mode is output as the switching signal SW.

  The target trajectory calculation unit 130 calculates the target trajectory Am by an existing method based on the vehicle state quantity Cv, and outputs it to the vehicle motion control unit 140.

  The vehicle motion control unit 140 includes a rudder angle command value generation unit 141. The rudder angle command value generation unit 141 is a rudder angle command that is a control target value of the steering angle based on the target trajectory Am and the vehicle state quantity Cv. A value θref is generated and output to the EPS side ECU 200.

  The EPS-side ECU 200 includes an EPS state quantity detection unit 210, a switching determination / gradual change gain generation unit 220, a steering angle control unit 300, an assist control unit 230, a switching unit 240, a current control / drive unit 250, and a motor current detector 38. I have.

  The EPS state quantity detection unit 210 receives signals from the angle sensor, torque sensor, and speed sensor, and detects the EPS state quantity. Specifically, the angle sensor detects the steering angle (the upper angle of the torsion bar) θh as the actual steering angle θr, the torque sensor detects the steering torque Tt, and the speed sensor detects the vehicle speed V. Further, the actual steering angular velocity ωr is calculated by performing a differential operation on the actual steering angle θr. The actual steering angle θr is input to the switching determination / gradual change gain generating unit 220 and the steering angle control unit 300, the actual steering angular speed ωr is input to the steering angle control unit 300, and the steering torque Tt is switched to / gradually changing gain generation unit. 220, the steering angle control unit 300 and the assist control unit 230 are input, and the vehicle speed V is input to the steering angle control unit 300 and the assist control unit 230. Note that the column steering angle (the lower angle of the torsion bar) may be used as the actual steering angle θr, a motor angle sensor (rotation angle sensor) may be provided, and the rotation angle of the motor may be the actual steering angle θr. Further, the actual steering angle θr and the vehicle speed V may be detected by the vehicle side ECU 100 and transmitted to the EPS side ECU 200. Further, the actual steering angular velocity ωr may be calculated from the difference calculation of the rotation angle detected by the motor angle sensor and the gear ratio, or may be calculated from the difference calculation of the actual steering angle θr. An LPF (low-pass filter) may be inserted in the final stage of the EPS state quantity detection unit 210 to reduce high-frequency noise. In this case, the actual steering angular velocity ωr may be calculated from the HPF (high-pass filter) and the gain. .

  The switching determination / gradual gain generating unit 220 is configured to perform automatic steering and manual steering based on the switching signal SW from the vehicle ECU 100, the steering torque Tt, the actual steering angle θr, and the target steering angle θt output from the steering angle control unit 300. Is determined, and the gradual gain is determined based on the determination result. As the gradual change gain, the steering angle control output gradual change gain Gfa1, the speed control gradual change gain Gfa2, the speed command gradual change gain Gfa3, the steering angle command gradual change gain Gfa4, the assist control output gradual change gain Gft1, and the assist map gradual change gain Gft2. Gfa1 and Gft1 are input to the switching unit 240, Gfa2, Gfa3 and Gfa4 are input to the steering angle control unit 300, and Gft2 is input to the assist control unit 230. The determination result of the switching determination is input to the steering angle control unit 300 as the steering state determination signal Js. Details of the switching determination / gradual change gain generation unit 220 will be described later.

  The steering angle control unit 300 performs the steering angle control by controlling the steering angle command value θref, the actual steering angle θr, the actual steering angular velocity ωr, the steering torque Tt, the vehicle speed V, the gradually changing gains Gfa2, Gfa3, and the like. A steering angle control current command value IrefP1 is calculated using Gfa4 and the steering state determination signal Js. The steering angle control current command value IrefP1 is input to the switching unit 240. The actual steering angular velocity ωr may be calculated not by the EPS state quantity detection unit 210 but by the steering angle control unit 300. Details of the steering angle control unit 300 will be described later.

  In order to perform assist control, the assist control unit 230 includes, for example, a current command value calculation unit 31, a current limiting unit 33, a compensation signal generation unit 34, and an addition unit 32A in the configuration example shown in FIG. Based on Tt and the vehicle speed V, an assist control current command value IrefT1 corresponding to the current command value Irefm in FIG. 2 is calculated using an assist map. However, unlike the configuration example of FIG. 2, the assist map gradual change gain Gft2 output from the switching determination / gradual change gain generation unit 220 is input and the output from the current command value calculation unit 31 (hereinafter referred to as “assist map output”). Current ”) and the multiplication result is input to the adder 32A. The assist map used in the current command value calculation unit 31 is a map that defines the characteristics of the current command value with respect to the steering torque Tt, and is a vehicle speed sensitive type that has a characteristic that the current command value decreases as the vehicle speed V increases. Note that the current limiter 33 and / or the compensation signal generator 34 may be omitted.

  The switching unit 240 calculates the current command value Iref using the steering angle control current command value IrefP1, the assist control current command value IrefT1, and the gradually changing gains Gfa1 and Gft1. Details of the switching unit 240 will be described later.

  The current control / drive unit 250 includes, for example, a subtraction unit 32B, a PI control unit 35, a PWM control unit 36, and an inverter 37 in the configuration example shown in FIG. 2, and is detected by the current command value Iref and the motor current detector 38. The motor is driven and controlled by the same operation as the configuration example of FIG.

  The plant 400 is a physical model to be controlled that simulates driver characteristics, EPS, and vehicle mechanical characteristics in steering the steering wheel, and includes a driver steering transmission characteristic 410 and a mechanical transmission characteristic 420. Since the mechanical system operates based on the steering wheel input torque Th generated by the steering of the driver and the motor current Im from the EPS side ECU 200, the state information EV related to the vehicle and the EPS is generated. Status information EV is output. The vehicle state quantity detection unit 110 of the vehicle side ECU 100 and the EPS state quantity detection unit 210 of the EPS side ECU 200 detect the vehicle state quantity Cv and the EPS state quantity from the state information EV, respectively. Since the steering wheel input torque Th due to the steering of the driver is generated according to the steering angle θh in the state information EV, the steering steering transmission characteristic 410 outputs the steering wheel input torque Th.

  Next, the switching determination / gradual change gain generation unit 220, the steering angle control unit 300, and the switching unit 240 of the EPS side ECU 200 will be described in detail.

  FIG. 4 shows a configuration example of the switching determination / gradual change gain generation unit 220. The switching determination / gradual change gain generation unit 220 includes a switching determination unit 221 and a gradual change gain generation unit 222, and the switching determination unit 221 is a manual operation. An input determination unit 223 and a steering state determination unit 224 are provided.

  The manual input determination unit 223 determines manual input using the steering torque Tt, the actual steering angle θr, and the target steering angle θt.

  FIG. 5 shows a configuration example of the manual input determination unit 223. The manual input determination unit 223 includes determination units 223A and 223B, a steering angle control model unit 228, and a subtraction unit 229. The determination unit 223A includes a smoothing filter unit. 225A and 225B, absolute value conversion units 226A and 226B, and a determination processing unit 227A. The determination unit 223B includes smoothing filter units 225C and 225D, absolute value conversion units 226C and 226D, and a determination processing unit 227B.

  The smoothing filter units 225A and 225B in the determination unit 223A have a smoothing filter (torque smoothing filter), and the steering torque Tt is smoothed by the smoothing filter A and the smoothing filter B, respectively. (Smoothing steering torque) Tta and Ttb are output. The smoothing filter A is slower in response to the output signal than the smoothing filter B, but has higher characteristics than the smoothing filter B in removing high-frequency noise components. The signal response is faster than that of the smoothing filter A, but the removal of high-frequency noise components is slightly inferior to that of the smoothing filter A. By using the smoothing filter B, which has a fast response, it is possible to respond to a steep manual input torque such as during emergency avoidance by steering and to facilitate determination when there is a manual input. The steering torques Tta and Ttb are input to the absolute value conversion units 226A and 226B. The absolute value conversion unit 226A calculates the absolute value (absolute value data) | Tta | of the steering torque Tta, and the absolute value conversion unit 226B calculates the absolute value of the steering torque Ttb. Each value (absolute value data) | Ttb | is output to the determination processing unit 227A. The determination processing unit 227A uses a plurality of predetermined threshold values (torque threshold values) TthA1, TthA2, TthA3, and TthB (0 ≦ TthA1 ≦ TthA2 ≦ TthA3 ≦ TthB) to determine three types of “with manual input”. One type of “no manual input” is determined. Specifically, when “absolute value | Tta | is greater than or equal to threshold value TthA3” or “absolute value | Ttb | is greater than or equal to threshold value TthB”, it is determined that “manual input is 3”, and “absolute value | Tta | is equal to threshold value TthA2”. As described above, when the value is less than the threshold value TthA3, it is determined that there is “manual input 2”. When the “absolute value | Tta | If | Tta | is less than the threshold value TthA1, it is determined that “no manual input”. The determination result is output as a manual input determination signal Jh1.

  The steering angle control model unit 228 calculates the estimated steering angle θi from the target steering angle θt, and the estimated steering angle θi is added to the subtraction unit 229 and input. The steering angle control model unit 228 sets a transmission characteristic of the actual steering angle θr with respect to the target steering angle θt in order to estimate the actual steering angle θr in the automatic steering state, and estimates the actual steering angle using the transmission characteristic. . If there is a difference between the estimated steering angle θi, which is the estimated actual steering angle, and the actual actual steering angle θr, it can be determined that there has been steering intervention by the driver. The transfer characteristic of the actual steering angle θr with respect to the target steering angle θt is defined by a transfer function, a differential equation (differential equation) or the like, and is generally obtained by inputting the target steering angle θt and outputting the actual steering angle θr by experiment or simulation. It is obtained by a simple identification method. To increase the estimation accuracy, the transfer characteristics are identified for each vehicle speed. The transfer function may be expressed by a mathematical expression based on a plant model that represents the frequency characteristics of the vehicle and the EPS and a control model that represents the frequency characteristics of the steering angle control unit.

  The subtraction unit 229 receives the actual steering angle θr as well as the estimated steering angle θi, and calculates an error dθ between the estimated steering angle θi and the actual steering angle θr. The error dθ is input to the determination unit 223B.

  The determination unit 223B performs smoothing of the error dθ on the error dθ by the smoothing filter units 225C and 225D each having a smoothing filter (error smoothing filter) with the same configuration and operation as the determination unit 223A. , Absolute values (absolute value data) | dθa | and | dθb | of the errors after smoothing (smoothing error) dθa and dθb are obtained by absolute value units 226C and 226D, respectively, and determination processing unit 227B obtains absolute value | dθa For | and | dθb |, there are three types of “manual input” using a plurality of predetermined threshold values (error threshold values) θthA1, θthA2, θthA3, and θthB (0 ≦ θthA1 ≦ θthA2 ≦ θthA3 ≦ θthB). And one type of “no manual input” determination. As in the case of the smoothing filter A and the smoothing filter B, the smoothing filter C and the smoothing filter D respectively included in the smoothing filter units 225C and 225D smooth the response of the output signal. Although it is slower than the filter D, the removal of the high-frequency noise component has characteristics superior to the smoothing filter D, and the smoothing filter D has a faster response of the output signal than the smoothing filter C, The removal of the noise component in the region has a characteristic slightly inferior to that of the smoothing filter C. For simplicity, the smoothing filter C may have the same characteristics as the smoothing filter A and the smoothing filter D may have the same characteristics as the smoothing filter B. The determination result is output as a manual input determination signal Jh2.

  The determination processing units 227A and 227B each perform determination using four threshold values. However, the number of threshold values is not limited to four, and determination may be performed using a threshold number other than four. . Thereby, flexible determination can be performed.

The steering state determination unit 224 determines the steering state from the switching signal SW from the vehicle side ECU 100 and the manual input determination signals Jh1 and Jh2. The steering state includes “automatic steering 1”, “automatic steering 2”, and “manual steering”, and “automatic steering 1” corresponds to a normal automatic steering state. In addition to the switching signal SW and the manual input determination signals Jh1 and Jh2, based on the steering state at the time of each data input (exactly the steering state one sample before, hereinafter referred to as the “previous steering state”), The latest steering state is determined. In the determination, the manual input determination signals Jh1 and Jh2 are assigned to either of the determination signals α and β. For example, when the manual input determination signal Jh1 is the determination signal α, the manual input determination signal Jh2 becomes the determination signal β, and the manual input When the determination signal Jh2 is the determination signal α, the manual input determination signal Jh1 becomes the determination signal β. In the present embodiment, the manual input determination signal Jh1 is the determination signal α, and the manual input determination signal Jh2 is the determination signal β. And determination is performed as follows.
[Condition 1]
When the immediately preceding steering state is “automatic steering 1” or “automatic steering 2”, the switching signal SW is “assist control mode” or the determination signal α is “manual input 3”, the steering state is determined to be “manual steering”. .
[Condition 2]
When the immediately preceding steering state is “automatic steering 1”, the switching signal SW is “steering angle control mode”, the determination signal α is “with manual input 2”, and the determination signal β is other than “with manual input 3” The steering state is determined as “automatic steering 2”.
[Condition 3]
When the immediately preceding steering state is “automatic steering 2”, the switching signal SW is “steering angle control mode”, the determination signal α is “manual input 1” or “manual input 2”, and the determination signal β is “hand input”. In cases other than “with input 3”, the steering state does not change and it is determined as “automatic steering 2”.
[Condition 4]
When the immediately preceding steering state is “automatic steering 2”, the switching signal SW is “steering angle control mode”, the determination signal α is “no manual input”, and the determination signal β is “no manual input”, the steering state Is determined as “automatic steering 1”.
[Condition 5]
When the immediately preceding steering state is “manual steering”, the switching signal SW is “steering angle control mode”, the determination signal α is “no manual input”, and the determination signal β is “no manual input”, the steering state is It determines with "automatic steering 1".

The above conditions 1 to 5 will be further detailed as shown in Tables 1 to 3 below. In Table 1, “-” means an arbitrary value (that is, not related to determination), “(continuation)” means that the steering state does not change, and the condition of each column is an AND condition. Judge by connecting. Table 2 shows the determination results when the immediately preceding steering state in Table 1 is “automatic steering 1” and the switching signal SW is “steering angle control mode”, and Table 3 shows the immediately preceding steering state in Table 1. Indicates the determination result when “automatic steering 2” is selected and the switching signal SW is “steering angle control mode”, α indicates “determination signal α”, and β indicates “determination signal β”.

The steering state is determined according to Tables 1 to 3, and the determination result is output to the gradual gain generating unit 222 as the steering state determination signal Js and also to the steering angle control unit 300. In the steering angle control unit 300, the steering state determination signal Js is used in setting a limit value in a variable rate limiting unit 320 described later and setting a limit value in a position control output variable limiting unit 345. Note that the steering state may be determined without using the switching signal SW.

  The gradually changing gain generation unit 222 determines a gradually changing gain based on the steering state determination signal Js. The gradually changing gain takes different values depending on the steering state, and the steering state is determined by the steering state determination signal Js. However, in the case of “automatic steering 2”, “automatic steering 1” is determined as the automatic steering state. Is left at the previous value.

  The gradual gains Gfa1, Gfa2, Gfa3 and Gfa4 are 100% in the automatic steering state and 0% in the manual steering state, and in the transition from the automatic steering state to the manual steering state and from the manual steering state to the automatic steering state, The value changes gradually. For example, when shifting from the automatic steering state to the manual steering state, the gradually changing gains Gfa1 to Gfa4 change as shown in FIG. That is, when the steering state determination signal Js changes from “automatic steering 1” to “manual steering” at time t1, the gradual gain gradually decreases from that time and becomes 0% at time t2. When shifting from the manual steering state to the automatic steering state, on the contrary, the gradual gain increases sequentially from the time when the steering state determination signal Js changes to “automatic steering 1”. When the value of the steering state determination signal Js is changed to “manual steering” while the gradually changing gain is decreasing or increasing (hereinafter, this state is referred to as “switching state”), the gradually changing gain is decreased. If it changes to "automatic steering 2", it will increase. In FIG. 6A, the gradual change gain in the switching state is linearly changed. However, in order to make the switching operation smooth, it may be changed like an S-shaped curve, and it changes linearly. The gradually changing gain may be used through an LPF, for example, a first-order LPF having a cutoff frequency of 2 Hz. Further, the gradual gains Gfa1 to Gfa4 do not have to be changed in conjunction with each other, and may be changed independently.

  The assist control output gradual change gain Gft1 is αt1 [%] (0 ≦ αt1 ≦ 150) in the automatic steering state and 100% in the manual steering state. As shown in FIG. As in the case of Gfa4, the value is gradually changed in the switching state.

  The assist map gradual change gain Gft2 is αt2 [%] (0 ≦ αt2 ≦ 150) in the automatic steering state and 100% in the manual steering state, and as shown in FIG. 6C, the gradual gains Gfa1 to Gfa4. As in the case of, the value is gradually changed in the switching state.

  There is “manual input 1” in the determination result of the manual input determination. By determining the steering state based on the determination result including the manual input and further determining the gradually changing gain, the state of “manual input 2” is obtained. It is possible to suppress chattering that occurs when the state is “no manual input”.

  A configuration example of the steering angle control unit 300 and the switching unit 240 is shown in FIG. The steering angle control unit 300 includes a steering angle command value variable limiting unit 310, a variable rate limiting unit 320, a handle vibration removing unit 330, a position control unit 340, a position control output variable limiting unit 345, a steering intervention compensation unit 350, a speed command value. A variable limiting unit 360, a steering angular velocity control unit 370, a steering wheel damping unit 380, a steering angle control current command value limiting unit 390, multiplication units 391 and 392, and addition units 393 and 394 are provided. The switching unit 240 includes a multiplication unit 241 and 242 and an adder 243 are provided.

  The rudder angle command value variable limiting unit 310 of the rudder angle control unit 300 steers an abnormal value or excessive value due to a communication error or the like with respect to the rudder angle command value θref for automatic steering received from the vehicle side ECU 100. In order to prevent input to the angle control, a limit value (upper limit value, lower limit value) is set and the limit is applied and output as the steering angle command value θref1. In order to set an appropriate limit value in the automatic steering state and the manual steering state, the limit value is set according to the steering angle command gradual change gain Gfa4. For example, as shown in FIG. 8, when the steering angle command gradual change gain Gfa4 is 100%, it is determined that the steering is in the automatic steering state, and the limit value indicated by the solid line is applied to limit the steering angle command gradual change gain. When Gfa4 is 0%, it is determined that it is in the manual steering state, and the absolute value is limited with a limit value smaller than that in the automatic steering state as indicated by the broken line. When the steering angle command gradual change gain Gfa4 is between 0 and 100%, it is determined that the switching state is set, and the value is limited by a value between the solid line and the broken line. In the switching state, the limit may be applied with a limit value in the solid automatic steering state or a limit value in the broken manual steering state. The magnitude of the upper limit value (absolute value) and the magnitude of the lower limit value may be different.

  In order to prevent the steering angle control current command value, which is the output of the steering angle control, from abruptly changing due to a sudden change in the steering angle command value θref, the variable rate limiting unit 320 applies a change amount to the steering angle command value θref1. Then, a limit value is set and the limit is applied, and the steering angle command value θref2 is output. For example, if the difference from the rudder angle command value θref1 one sample before is the amount of change, and the absolute value of the amount of change is greater than a predetermined value (limit value), The steering angle command value θref1 is added or subtracted and output as the steering angle command value θref2, and if it is equal to or less than the limit value, the steering angle command value θref1 is output as it is as the steering angle command value θref2. As in the case of the steering angle command value variable limiting unit 310, an appropriate limit value is set in the automatic steering state and the manual steering state, but the limit value may be changed without interlocking with the gradually changing gain. The limit value is set according to the steering state determination signal Js output from the switching determination / gradual gain generating unit 220. When the steering state determination signal Js is “automatic steering 1”, the limit value is a predetermined value. When the steering state determination signal Js is “automatic steering 2” or “manual steering”, the limit value is zero. The angle command value θref2 is made constant without changing. Instead of setting a limit value for the absolute value of the change amount, an upper limit value and a lower limit value may be set for the change amount to limit the change amount.

  Here, the effect of setting the limit value of the variable rate limiting unit 320 according to the determination of the steering state in the switching determination / gradual change gain generation unit 220 and the determination result will be described using an example. It is assumed that the determination unit 223A and the determination unit 223B of the manual input determination unit 223 perform the same determination.

  FIG. 9 shows the result of manual input determination and the change in steering state when there is an obstacle such as an object, a puddle, or ice on the road during automatic driving, and a driver intervention occurs to avoid the obstacle. It shows the situation.

  Steering angle control without shifting to “manual steering” when the steering intervention is such that the obstacle is slightly to the right and the hand input is weaker than the level judged as “manual input 3”. Will continue. Therefore, the vehicle-side ECU 100 updates the steering angle command value so that the steering wheel is turned to the left side in order to return the vehicle that has approached the right side to the center by the driver's steering intervention. And the steering by the steering angle command value from the vehicle side ECU 100 that wants to maintain the center collide with each other. Therefore, in order to prioritize the driver's steering intervention from the point of safety priority, when the manual input determination becomes “2 with manual input” at the point P1, the steering state becomes the “automatic steering 2” state, The limit value of the variable rate limiting unit 320 is set to zero and the steering angle command value is set to a constant value by the steering state determination signal Js. Thereby, smooth steering intervention can be realized without being affected by the update of the steering angle command value.

  After dodging the obstacle, the driver's steering intervention is weakened, and the steering state remains “automatic steering 2” even if the manual input determination becomes “manual input 1” at the point P2, and further the steering intervention When the hand input determination becomes “no manual input” at the point P3, the steering state transitions to “automatic steering 1”. In this way, once “manual input 1” is set, chattering and the like due to switching between “automatic steering 1” and “automatic steering 2” can be prevented. After “automatic steering 1” is reached, the steering wheel command value becomes a normal steering angle and the operation returns to automatic operation.

  Thus, even when there is a steering intervention by the driver to dodge the obstacle, the transition to “manual steering” is not performed, and seamless steering can be realized.

  Returning to the description of the configuration example shown in FIG. 7, the multiplication unit 391 multiplies the steering angle command value θref2 by the steering angle command gradual change gain Gfa4 and outputs the result as the steering angle command value θref3. As a result, a target steering angle θt output from a steering wheel vibration removal unit 330 (described later) in the switching state from the automatic steering state to the manual steering state can be made asymptotic to zero, and the steering angle control can be applied to the neutral state.

  The steering wheel vibration removal unit 330 reduces the vibration frequency component included in the steering angle command value θref3. When the steering angle command is changing during automatic steering, a frequency component (about 10 Hz) that excites vibration due to the spring property of the torsion bar and the inertial moment of the steering wheel is generated in the steering angle command value θref3. The steering wheel vibration frequency component included in the steering angle command value θref3 is reduced by filter processing using an LPF, a notch filter or the like, or phase delay compensation, and the target steering angle θt is output. As a filter, any filter may be used as long as the gain of the handle vibration frequency band can be lowered and mounted on the ECU. By installing a multiplication unit 391 that multiplies the steering angle command gradual change gain Gfa4 in front of the steering wheel vibration removal unit 330, it is possible to reduce the handle vibration frequency component generated by multiplication of the steering angle command gradual change gain Gfa4. . The target steering angle θt is output to the position control unit 340 and the switching determination / gradual gain generating unit 220. In the case where the handle vibration frequency component is very small, the handle vibration removing unit 300 may be omitted.

  The position control unit 340 calculates a steering angular velocity command value ωref0 for bringing the actual steering angle θr closer to the target steering angle θt based on the deviation between the target steering angle θt and the actual steering angle θr by P (proportional) control.

  A configuration example of the position control unit 340 is shown in FIG. The position control unit 340 includes a proportional gain unit 341 and a subtraction unit 342. A subtraction unit 342 calculates a deviation θe (= θt−θr) between the target steering angle θt and the actual steering angle θr, and the deviation θe is input to the proportional gain unit 341. The proportional gain unit 341 calculates a steering angular velocity command value ωref0 by multiplying the deviation θe by the proportional gain Kpp.

  The position control output variable limiter 345 sets a limit value for the steering angular speed command value ωref0, limits the steering angular speed command value ωref0, and outputs a steering angular speed command value (restricted steering angular speed command value) ωref1. The limit value is set according to the steering state determination signal Js in order to prevent a sudden change in the steering angle when the steering wheel is released after the steering intervention by the driver. That is, when the steering state determination signal Js is “automatic steering 1”, the limit value is set to a predetermined setting value (hereinafter referred to as “setting value A”), and the steering state determination signal Js is “automatic steering 2” or In the case of “manual steering”, the limit value is set to a set value smaller than the set value A (hereinafter referred to as “set value B”). In the case of “automatic steering 2” or “manual steering”, by setting a setting value B that is smaller than the setting value A in “automatic steering 1”, even if the steering wheel is released, the steering wheel becomes “automatic steering 1”. A sudden change in the rudder angle can be prevented. As a method of applying the limit, even if a limit value is set for the magnitude (absolute value) of the steering angular velocity command value ωref0, the upper limit value and the lower limit value are set for the steering angular velocity command value ωref0. And you can put a limit. In the latter case, the set value A and the set value B have two values, an upper limit value and a lower limit value, respectively.

  The steering intervention compensation unit 350 calculates a steering angular velocity command value (compensated steering angular velocity command value) ωref2 for steering intervention compensation according to the steering torque Tt and the actual steering angle θr. Since the steering angular velocity command value ωref is obtained by adding the steering angular velocity command value ωref2 and the steering angular velocity command value ωref1 from the position control output variable limiting unit 345, the function of the steering intervention compensation unit 350 reduces the generation of steering torque. A steering angular velocity command value can be generated in the direction, and steering intervention during automatic steering can be realized.

  A configuration example of the steering intervention compensation unit 350 is shown in FIG. The steering intervention compensation unit 350 includes a basic map unit 351, a steering angular velocity calculation unit 352, a damper gain unit 353, a multiplication unit 354, and a subtraction unit 355. The steering angular velocity calculation unit 352 includes a differentiation unit 352A and an LPF 352B.

  The steering torque Tt input to the steering intervention compensation unit 350 is input to the basic map unit 351, and the actual steering angle θr is input to the steering angular velocity calculation unit 352. The rudder angular velocity calculation unit 352 differentiates the actual steering angle θr by the differentiating unit 352A, and further performs filter processing by the LPF by the LPF 352B to calculate the rudder angular velocity ωs.

  The basic map unit 351 has a basic map, and obtains a steering angular speed command value (first speed command value) ωref2a using the basic map. The basic map is a map that defines the characteristics of the steering angular velocity command value with respect to the steering torque, and changes depending on the vehicle speed. Therefore, the steering angular velocity command value ωref2a is obtained from the steering torque Tt and the vehicle speed V.

  The basic map is adjusted by tuning. For example, as shown in FIG. 12, the steering angular velocity command value increases as the magnitude (absolute value) of the steering torque increases, but decreases as the vehicle speed increases. To do. The higher the vehicle speed, the smaller the steering angular velocity command value, and the heavier feel (steering feel, steering feeling), and the lower the vehicle speed, the lighter the feel. Since the assist map used in the assist control unit 230 also has a characteristic that the assist control current command value decreases as the vehicle speed increases, the steering angular speed command value and the assist when the driver has intervened during high-speed driving. An increase in the control current command value is suppressed, and a safe steering is possible without a sudden steering. In FIG. 12, the map is configured according to the magnitude of the steering torque. However, the map may be configured in accordance with the positive and negative steering torque Tt. In this case, the map is generated depending on whether the steering torque is positive or negative. The mode of change may be changed.

  The damper gain unit 353 outputs a damper gain Gd that is multiplied by the steering angular velocity ωs. The steering angular speed ωs multiplied by the damper gain Gd by the multiplication unit 354 is subtracted from the steering angular speed command value ωref2a by the subtraction unit 355 as the steering angular speed command value (second speed command value) ωref2b, and the subtraction result is the steering angular speed command value. ωref2.

  The damper gain Gd is obtained from a damper gain map that the damper gain unit 353 has. By making this damper gain map a vehicle speed sensitive type, it is possible to give a feeling of viscosity to the feel in steering intervention during automatic steering. It can also be used as a function to alleviate a steep change in rudder angle when a hand is released from the steering wheel to return to automatic steering after steering intervention. For example, as shown in FIG. 13, by increasing the damper gain Gd as the vehicle speed increases, it is possible to increase the feeling of viscosity.

  The damper gain unit 353 and the multiplication unit 354 constitute a damper calculation unit. Further, as the steering angular speed multiplied by the damper gain Gd, the actual steering angular speed ωr input to the steering angle control unit 300 may be used instead of the steering angular speed ωs output from the steering angular speed calculation unit 352. In this case, the rudder angular velocity calculation unit 352 is unnecessary. As the rotational speed information, the motor speed may be used instead of the steering angular speed.

  In the addition unit 393 of the steering angle control unit 300, the steering angular velocity command value ωref1 output from the position control output variable limiting unit 345 and the steering angular velocity command value ωref2 output from the steering intervention compensation unit 350 are added, and the steering angular velocity command value is added. Output as ωref.

  In the multiplication unit 392, the steering angular velocity command value ωref is multiplied by the speed command gradual change gain Gfa3 and output as the steering angular velocity command value ωrefg. The speed command gradual change gain Gfa3 is used to realize smooth switching when switching from the manual steering state to the automatic steering state. Note that the speed command gradual change gain Gfa3 changes in synchronization with the steering angle control output gradual change gain Gfa1 multiplied by the steering angle control current command value IrefP1 (not necessarily perfect synchronization).

  The speed command value variable limiting unit 360 sets a limit value (upper limit value, lower limit value) for the steering angular speed command value ωrefg, limits the steering angular speed command value ωrefg, and outputs a target steering angular speed ωt. The limit value is set according to the speed command gradual change gain Gfa3. For example, when the speed command gradual change gain Gfa3 is less than a predetermined threshold, the magnitude (absolute value) of the limit value is set to a small value as shown by the broken line in FIG. 14, and the magnitude of the limit value is indicated by a solid line above it. Increase the value to The predetermined threshold value is an arbitrary value of the speed command gradual change gain Gfa3 in the switching state. When Gfa3 is less than the predetermined threshold value, the magnitude of the limit value is fixed at a small value of a broken line, and Gfa3 is set to the predetermined threshold value. If it exceeds, the limit value may be gradually increased up to the solid line. The size of the upper limit value and the size of the lower limit value may be different.

  The rudder angular velocity control unit 370 inputs the target rudder angular velocity ωt, the actual rudder angular velocity ωr, and the speed control gradually changing gain Gfa2, and obtains the rudder angle control current command value IrefW such that the actual rudder angular velocity ωr follows the target rudder angular velocity ωt. It is calculated by IP control (proportional advance type PI control).

  A configuration example of the rudder angular velocity control unit 370 is shown in FIG. The rudder angular velocity control unit 370 includes gain multiplication units 371 and 372, an integration unit 373, subtraction units 374 and 375, and a multiplication unit 376.

  The gain multiplication unit 371 multiplies the deviation ωe (= ωt−ωr) between the target steering angular velocity ωt and the actual steering angular velocity ωr calculated by the subtraction unit 374 by the gain Kvi, and outputs an operation amount D1. The integrating unit 373 integrates the operation amount D1 and calculates the control amount Ir1. The multiplication unit 376 multiplies the control amount Ir1 by the speed control gradual change gain Gfa2, and outputs the result as the control amount Ir3. The multiplication of the speed control gradual change gain Gfa2 is performed in order to realize smooth switching between the manual steering state and the automatic steering state, thereby mitigating the influence of integration value accumulation in the steering angular speed control at the time of switching. be able to. The gain multiplication unit 372 multiplies the actual steering angular speed ωr by the gain Kvp and outputs a control amount Ir2. In the subtraction unit 375, a deviation (Ir3-Ir2) between the control amounts Ir3 and Ir2 is calculated and output as a steering angle control current command value IrefW. As the integration of the integration unit 373, any method can be used as long as it is an integration method that can be implemented. When using the pseudo-integration, the integration unit 373 may be configured with a first-order lag transfer function and gain. . Further, the speed control gradually changing gain Gfa2 may be changed in synchronization with the steering angle control output gradually changing gain Gfa1.

  The rudder angular speed control unit 370 uses IP control, but a generally used control method may be used as long as the actual rudder angular speed can be made to follow the target rudder angular speed. . For example, PI control, 2-degree-of-freedom PI control, model reference control, model matching control, robust control, and a control method in which compensation means for estimating a disturbance and canceling a disturbance component are combined in part may be used.

  The handle vibration damping unit 380 dampens the vibration of the handle based on the steering torque Tt that is a torsion bar torque signal. The handle vibration removing unit 330 also has an effect on the handle vibration during automatic steering, but the handle damping unit 380 can further improve the effect. The steering wheel damping unit 380 performs damping of the steering wheel vibration by gain and phase compensation, and outputs a steering angle control current command value IrefV that works in a direction to eliminate torsion of the torsion bar. In addition, the handle damping unit 380 works in the direction of reducing the twist angle, and also has the effect of reducing the uncomfortable feeling of catching at the time of manual input intervention by the driver.

  A configuration example of the handle damping unit 380 is shown in FIG. The handle damping unit 380 includes a gain unit 381 and a damping phase compensation unit 382. The gain unit 381 multiplies the steering torque Tt by the gain Kv and outputs a control amount Irv. The vibration suppression phase compensation unit 382 is constituted by, for example, a primary filter, and converts the control amount Irv into a steering angle control current command value IrefV. You may comprise not a primary filter but a phase compensation filter more than secondary.

  In the addition unit 394, the steering angle control current command value IrefW output from the steering angular speed control unit 370 and the steering angle control current command value IrefV output from the steering wheel damping unit 380 are added, and the result is used as the steering angle control current command value IrefP2. Is output.

  The steering angle control current command value limiting unit 390 applies a limit to the steering angle control current command value IrefP2 by setting a limit value (upper limit value, lower limit value) in order to prevent excessive output. Command value IrefP1 is output. For example, as shown in FIG. 17, an upper limit value and a lower limit value are set to limit the steering angle control current command value IrefP2. The magnitude of the upper limit value (absolute value) and the magnitude of the lower limit value may be different.

  The switching unit 240 includes multiplication units 241 and 242 and an addition unit 243.

  In the multiplication unit 241 of the switching unit 240, the steering angle control current command value IrefP1 output from the steering angle control unit 300 is multiplied by the steering angle control output gradual change gain Gfa1 output from the switching determination / gradual change gain generation unit 220. And output as a steering angle control current command value IrefP. The steering angle control output gradual change gain Gfa1 is used to smoothly switch between the manual steering state and the automatic steering state, and to realize a sense of incongruity and safety for the driver. In the multiplication unit 242, the assist control current command value IrefT1 output from the assist control unit 230 is multiplied by the assist control output gradual change gain Gft1, and is output as the assist control current command value IrefT. The assist control output gradual gain Gft1 is used to smoothly switch between the manual steering state and the automatic steering state, and to realize steering intervention by the driver during automatic driving. In the adding unit 243, the steering angle control current command value IrefP and the assist control current command value IrefT are added and output as a current command value Iref.

  The assist map gradual change gain Gft2 used in the assist control unit 230 is also used for the same purpose as the assist control output gradual change gain Gft1. In the automatic steering state, as shown in FIGS. 6B and 6C, Gft1 is set to αt1, Gft2 is set to αt2, and αt1 and αt2 are adjusted to improve the stability of the system and to vibrate. Can be suppressed. Further, if it is possible to maintain the stability of the system in the automatic steering state, αt1 may be simply set to 0% and αt2 may be set to 100%. In this case, since αt1 is 0%, the assist control current command value IrefT becomes a zero command, and steering intervention can be realized even when the assist control is eliminated.

  In such a configuration, an operation example of the EPS side ECU 200 will be described with reference to flowcharts of FIGS.

  When the operation is started, the EPS state quantity detection unit 210 detects the actual steering angle θr, the steering torque Tt, and the vehicle speed V (step S10), and switches the actual steering angle θr to the switching determination / gradual change gain generation unit 220 and the steering angle control unit. 300, the steering torque Tt is output to the switching determination / gradual gain generating unit 220, the steering angle control unit 300, and the assist control unit 230, and the vehicle speed V is output to the steering angle control unit 300 and the assist control unit 230, respectively. Further, the EPS state quantity detection unit 210 calculates the actual steering angular velocity ωr from the actual steering angle θr (step S20), and outputs it to the steering angle control unit 300.

  The target steering angle θt one sample before output from the steering angle control unit 300 is input to the switching determination / gradual change gain generation unit 220 to which the steering torque Tt and the actual steering angle θr are input. The switching determination / gradual change gain generation unit 220 uses them to make a switching determination between automatic steering and manual steering based on the input of the switching signal SW output from the vehicle ECU 100, and gradually changes based on the determination result. The gain is determined (step S30), and gradually changing gains Gfa2, Gfa3, and Gfa4 are output to the steering angle control unit 300, Gft2 to the assist control unit 230, and Gfa1 and Gft1 to the switching unit 240, respectively. Further, the steering state determination signal Js is output to the steering angle control unit 300. Details of the operation of the switching determination / gradual change gain generation unit 220 will be described later.

  The steering angle control unit 300 includes a steering angle command value θref from the vehicle side ECU 100, an actual steering angle θr from the EPS state quantity detection unit 210, an actual steering angular velocity ωr, a steering torque Tt and a vehicle speed V, and a switching determination / gradual change gain. The gradual gain Gfa2, Gfa3, Gfa4 and the steering state determination signal Js from the generation unit 220 are input, and the steering angle control current command value IrefP1 is calculated using them (step S40) and output to the switching unit 240. Details of the operation of the steering angle control unit 300 will be described later.

  The assist control unit 230 inputs the steering torque Tt, the vehicle speed V, and the assist map gradual gain Gft2, and calculates an assist map output current (current value) by the same operation as the current command value calculation unit 31 shown in FIG. (Step S50). Then, the assist map output current is multiplied by the assist map gradual change gain Gft2 (step S60), and the multiplication result is the same as that of the adder 32A, current limiter 33, and compensation signal generator 34 shown in FIG. To calculate an assist control current command value IrefT1 (step S70) and output it to the switching unit 240.

  The switching unit 240 multiplies the input steering angle control current command value IrefP1 by the steering angle control output gradual gain Gfa1 by the multiplication unit 241 (step S80), and adds the steering angle control current command value IrefP that is the multiplication result. Output to the unit 243. Further, the input assist control current command value IrefT1 is multiplied by the assist control output gradual change gain Gft1 by the multiplication unit 242 (step S90), and the multiplication result of the assist control current command value IrefT is output to the addition unit 243. The adding unit 243 adds the steering angle control current command value IrefP and the assist control current command value IrefT (step S100), and outputs the current command value Iref as the addition result to the current control / drive unit 250.

  The current control / driving unit 250 performs the same operation as the subtraction unit 32B, the PI control unit 35, the PWM control unit 36, and the inverter 37 shown in FIG. Using the current Im, the motor current Im is controlled so as to follow the current command value Iref (step S110), and the drive of the motor is controlled.

  Details of an operation example of the switching determination / gradual change gain generation unit 220 will be described with reference to the flowcharts of FIGS. 19 and 20. In the steering state determination unit 224, “manual steering” is set as the initial value in the immediately preceding steering state, “assist control mode” is set as the initial value for the switching signal SW to be held, and “manual steering” is set as the initial value in the steering state determination signal Js. Suppose that it is set.

  The input steering torque Tt, target steering angle θt, and actual steering angle θr are input to the manual input determination unit 223 in the switching determination unit 221. In the manual input determination unit 223, the steering torque Tt is input to the determination unit 223A, the target steering angle θt is input to the steering angle control model unit 228, and the actual steering angle θr is input to the subtraction unit 229.

  The steering angle control model unit 228 calculates the estimated steering angle θi from the target steering angle θt (step S210). The estimated steering angle θi is added to the subtraction unit 229, the actual steering angle θr is subtracted (step S220), and the error dθ (= θi−θr) is input to the determination unit 223B.

  The determination unit 223A smoothes the steering torque Tt with the smoothing filter units 225A and 225B, and obtains the absolute values | Tta | and | Ttb | of the steering torques Tta and Ttb after smoothing with the absolute value conversion units 226A and 226B (step). S230). The absolute values | Tta | and | Ttb | are input to the determination processing unit 227A. If the absolute value | Ttb | is equal to or greater than the threshold value TthB (step S240), the determination processing unit 227A determines that “manual input is 3” (step S250). When the absolute value | Ttb | is less than the threshold value TthB (step S240), if the absolute value | Tta | is equal to or greater than the threshold value TthA3 (step S260), it is determined that “manual input is 3” (step S250), and the absolute value | Tta If | is less than threshold value TthA3 and greater than or equal to threshold value TthA2 (step S270), it is determined that “manual input is 2” (step S280), and if absolute value | Tta | is less than threshold value TthA2 and greater than or equal to threshold value TthA1 (step S290), It is determined that “manual input is 1” (step S300). If the absolute value | Tta | is less than the threshold value TthA1 (step S290), it is determined that “manual input is not present” (step S310). The determination result is output to the steering state determination unit 224 as a manual input determination signal Jh1.

  The determination unit 223B smoothes the error dθ by the smoothing filter units 225C and 225D, and obtains the absolute values | dθa | and | dθb | of the smoothed errors dθa and dθb by the absolute value conversion units 226C and 226D (step S320). . The absolute values | dθa | and | dθb | are input to the determination processing unit 227B. If the absolute value | dθb | is equal to or greater than the threshold θthB (step S330), the determination processing unit 227B determines that “manual input is 3” (step S340). When the absolute value | dθb | is less than the threshold θthB (step S330), if the absolute value | dθa | is equal to or greater than the threshold θthA3 (step S350), it is determined that “manual input is 3” (step S340), and the absolute value | dθa. If | is less than threshold θthA3 and greater than or equal to threshold θthA2 (step S360), it is determined that “manual input is 2” (step S370). If absolute value | dθa | is less than threshold θthA2 and greater than or equal to threshold θthA1 (step S380), It is determined that there is “manual input 1” (step S390). If the absolute value | dθa | is less than the threshold θthA1 (step S380), it is determined that there is no manual input (step S400). The determination result is output to the steering state determination unit 224 as a manual input determination signal Jh2. Note that the operation of the determination unit 223A and the operation of the determination unit 223B may be executed in parallel, in reverse order.

  The steering state determination unit 224 confirms whether or not the switching signal SW is input (step S410). If the switching signal SW is input, the steering state determination unit 224 updates the value of the held switching signal SW (step S420). Then, the input manual input determination signals Jh1 and Jh2 are set as the determination signals α and β, respectively, and the steering state is determined according to the condition determination of Tables 1 to 3 using the immediately preceding steering state and the switching signal SW (step S430). . The determination result is output as the steering state determination signal Js to the gradual gain generating unit 222 and the steering angle control unit 300, and held as the immediately preceding steering state in the next determination (step S440).

  The gradual gain generation unit 222 checks the value of the steering state determination signal Js (step S450). When the steering state determination signal Js is “manual steering”, the gradual gains (Gfa1 to Gfa4, Gft1, and Gft2) are changed to values in the manual steering state (0% for Gfa1 to Gfa4 and 100% for Gft1 and Gft2). (Step S460). When the steering state determination signal Js is “automatic steering 1”, each gradual gain is changed to a value in an automatic steering state (100% for Gfa1 to Gfa4, αt1 for Gft1, and αt2 for Gft2) (step S470). When the steering state determination signal Js is “automatic steering 2”, the gradually changing gains are left as they are.

  Details of an operation example of the rudder angle control unit 300 will be described with reference to the flowcharts of FIGS.

  The steering angle command value variable limiting unit 310 confirms the value of the input steering angle command gradual change gain Gfa4 (step S610), and when Gfa4 is 0%, the limit value is shown in “manual steering” shown in FIG. (Step S620), if Gfa4 is 100%, the limit value for "automatic steering" shown in FIG. 8 is set (step S630). If Gfa4 is 0 to 100%, an intermediate value is set as the limit value. (Step S640). Then, using the set limit value, the steering angle command value θref input from the vehicle ECU 100 is limited (step S650), and the steering angle command value θref1 is output.

  The steering angle command value θref1 is input to the variable rate limiting unit 320 together with the steering state determination signal Js and the actual steering angle θr. The variable rate limiting unit 320 checks the value of the steering state determination signal Js (step S660). If the steering state determination signal Js is “manual steering” or “automatic steering 2”, the variable rate limiting unit 320 sets the limit value to zero (step S670, S681) In the case of “manual steering”, the value of the steering angle command value θref1 that is held one sample before is set to the value of the actual steering angle θr (step S671). Step S671 is a state in which the value at the end of the previous steering angle control remains when the steering angle control is started. If the value is used as it is, the steering wheel may change suddenly due to a sudden change in the steering angle command value. Therefore, this is a measure for suppressing a sudden change by starting in a state in which it matches the actual steering angle θr. When the steering state determination signal Js is “automatic steering 1”, the limit value is set to a predetermined value (step S680). Then, a difference (amount of change) between the steering angle command value θref1 and the steering angle command value θref1 one sample before is calculated (step S690). When the absolute value of the change amount is larger than the limit value (step S700), the steering angle command value θref1 is added or subtracted so that the absolute value of the change amount becomes the limit value (step S710), and is output as the steering angle command value θref2. (Step S720). When the absolute value of the change amount is equal to or less than the limit value (step S700), the steering angle command value θref1 is output as it is as the steering angle command value θref2 (step S720).

  The steering angle command value θref2 is multiplied by the steering angle command gradual gain Gfa4 by the multiplication unit 391 (step S730), and is output as the steering angle command value θref3. The steering angle command value θref3 is input to the steering wheel vibration removal unit 330. .

  The steering wheel vibration removal unit 330 reduces the vibration frequency component with respect to the steering angle command value θref3 (step S740), and outputs it to the position control unit 340 and the switching determination / gradual change gain generation unit 220 as the target steering angle θt.

  The target steering angle θt is added to the subtraction unit 342 in the position control unit 340. The actual steering angle θr is subtracted and input to the subtraction unit 342, and the subtraction unit 342 obtains the deviation θe between the target steering angle θt and the actual steering angle θr (step S750). The deviation θe is input to the proportional gain unit 341, and the proportional gain unit 341 multiplies the deviation θe by the proportional gain Kpp to calculate the steering angular velocity command value ωref0 (step S760). The steering angular velocity command value ωref0 is input to the position control output variable limiting unit 345.

  The position control output variable limiting unit 345 receives the steering state determination signal Js together with the steering angular velocity command value ωref0, and confirms the value of the steering state determination signal Js (step S770). When the steering state determination signal Js is “manual steering” or “automatic steering 2”, the limit value is set to the set value B (steps S780 and S800), and when it is “automatic steering 1”, the limit value is set to the set value A ( Step S790). Then, using the set limit value, the steering angular velocity command value ωref0 is limited (step S810), and the steering angular velocity command value ωref1 is output. The steering angular velocity command value ωref1 is input to the adding unit 393.

  On the other hand, the steering intervention compensation unit 350 inputs the vehicle speed V, the steering torque Tt, and the actual steering angle θr, and calculates the steering angular velocity command value ωref2 (step S820). An example of the operation of the steering intervention compensation unit 350 will be described with reference to FIG.

  The vehicle speed V input to the steering intervention compensation unit 350 is input to the basic map unit 351 and the damper gain unit 353, the steering torque Tt is input to the basic map unit 351, and the actual steering angle θr is input to the steering angular velocity calculation unit 352.

  The basic map unit 351 obtains the steering angular velocity command value ωref2a based on the steering torque Tt and the vehicle speed V using the basic map shown in FIG. 12 (step S821). The steering angular velocity command value ωref2a is added to the subtraction unit 355.

  The rudder angular velocity calculation unit 352 differentiates the actual steering angle θr by the differentiating unit 352A (step S822), further executes low-pass filter processing by the LPF 352B, and outputs the result to the multiplying unit 354 as the rudder angular velocity ωs.

  The damper gain unit 353 obtains a damper gain Gd based on the vehicle speed V using the damper gain map shown in FIG. 13 (step S823), and the damper gain Gd is input to the multiplication unit 354 and multiplied by the steering angular speed ωs (step S824). ), The multiplication result is subtracted and input to the subtracting unit 355 as the steering angular velocity command value ωref2b.

  The subtractor 355 subtracts the steering angular velocity command value ωref2b from the steering angular velocity command value ωref2a (step S825), and outputs the steering angular velocity command value ωref2 (step S826).

  The steering angular velocity command value ωref2 output from the steering intervention compensation unit 350 is input to the addition unit 393.

  The steering angular velocity command values ωref1 and ωref2 input to the adding unit 393 are added (step S840) and output as the steering angular velocity command value ωref. The steering angular speed command value ωref is multiplied by the speed command gradual gain Gfa3 by the multiplication unit 392 (step S850), and is input to the speed command value variable limiting unit 360 as the steering angular speed command value ωrefg.

  The speed command value variable limiting unit 360 inputs the speed command gradually changing gain Gfa3 together with the steering angular speed command value ωrefg, and checks the value of the speed command gradually changing gain Gfa3 (step S860). If Gfa3 is less than the predetermined threshold value, the limit value is set to a “Gfa3 small” limit value shown in FIG. 14 (step S870), and if it is equal to or greater than the predetermined threshold value, the limit value is set to “Gfa3 large” (step S870). Step S880). Using the set limit value, the steering angular velocity command value ωrefg is limited (step S890), and the target steering angular velocity ωt is output. The target rudder angular velocity ωt is input to the rudder angular velocity control unit 370.

  The steering angular speed control unit 370 inputs the actual steering angular speed ωr and the speed control gradual change gain Gfa2 together with the target steering angular speed ωt. The target rudder angular velocity ωt is added to the subtractor 374, the actual rudder angular velocity ωr is subtracted to the subtractor 374, and the deviation ωe between the target rudder angular velocity ωt and the actual rudder angular velocity ωr is input to the gain multiplier 371 (step S900). ). The gain multiplication unit 371 multiplies the deviation ωe by the gain Kvi (step S910), and outputs an operation amount D1. The operation amount D1 is input to the integration unit 373, and the integration unit 373 integrates the operation amount D1 to calculate the control amount Ir1 (step S920) and outputs it to the multiplication unit 376. The multiplier 376 multiplies the control amount Ir1 by the speed control gradual change gain Gfa2 (step S930), and outputs the control amount Ir3. The control amount Ir3 is added to the subtraction unit 375. The actual steering angular velocity ωr is also input to the gain multiplication unit 372. The gain multiplication unit 372 multiplies the actual steering angular velocity ωr by the gain Kvp (step S940), outputs the control amount Ir2, and the control amount Ir2 is the subtraction unit. Subtracted at 375. In the subtraction unit 375, the deviation between the control amounts Ir3 and Ir2 is calculated (step S950), and is output to the addition unit 394 as the steering angle control current command value IrefW.

  The steering torque Tt is also input to the steering wheel damping unit 380. In the steering vibration damping unit 380, the gain unit 381 multiplies the input steering torque Tt by the gain Kv (step S960), and outputs the control amount Irv. The controlled variable Irv is phase-compensated by the vibration suppression phase compensator 382 (step S970) and output as the steering angle control current command value IrefV. The steering angle control current command value IrefV is output to the adding unit 394.

  The steering angle control current command values IrefW and IrefV input to the adding unit 394 are added (step S980) and input to the steering angle control current command value limiting unit 390 as the steering angle control current command value IrefP2.

  The steering angle control current command value limiting unit 390 limits the steering angle control current command value IrefP2 using the limit value of the characteristic shown in FIG. 17, and outputs the steering angle control current command value IrefP1 (step). S990).

  Note that the operation of the rudder angle control unit 300 and the operation of the assist control unit 230 may be executed in parallel or in reverse order. In the operation of the steering angle control unit 300, the operation up to the calculation of the steering angular velocity command value ωref1 input to the addition unit 393, the operation up to the calculation of the steering angular velocity command value ωref2, and the steering angle control current command value input to the addition unit 394. The operations up to the calculation of IrefW and the operation up to the calculation of the steering angle control current command value IrefV may be executed in reverse or in parallel.

  The effect of this embodiment is demonstrated based on a simulation result.

In the simulation, a vehicle motion model and a driver's steering model are set as the plant model of the plant 400. As a vehicle movement model, for example, Masato Abe, “Automotive Movement and Control”, Tokyo Denki University, Tokyo Denki University Press, issued on September 20, 2009, First Edition, 2nd Edition, Chapter 3 (p.49) -105) Using models shown in Chapter 4 (p.107-130) and Chapter 5 (p.131-147), as a steering model, for example, Daisuke Yokoi, master's thesis, “musculoskeletal characteristics of arms” "Study on Evaluation of Steering Feel of Cars Taking into Account", Department of Mechanical Engineering, Graduate School of Engineering, Mie University, accepted February 6, 2007, Chapter 2 (p.3-5), Chapter 3 (p.6) -9) You may use the model shown by (references), It is not limited to these, You may use another model. A steering model used in this simulation is shown in FIG. 24 for reference. In FIG. 24, _Carm and _Cpalm are viscosity coefficients, _Karm and _Kpalm are spring constants, and _Iarm is the moment of inertia of the arm. The steering wheel steering angle θh output from the mechanical model (mechanical transmission characteristic) is input to the steering model (driver steering transmission characteristic), and the steering wheel input torque Th output from the steering model is output to the mechanical model. The target angle described in the reference is hereinafter referred to as a driver target angle (steering target angle) θarm. Furthermore, in the reference literature, the mass system of the arm is added to the column moment of inertia, but the force applied from the palm to the steering wheel is defined as the steering wheel input torque Th, so that it is between the palm angle and the steering wheel steering angle θh. The values of the acting spring constant K _palm and viscosity coefficient C _palm are sufficiently large, and there is no problem even if the simulation is performed. In this simulation, this is the case. Further, the followability of the motor current with respect to the current command value is sufficiently fast, and the influence of the operation of the current control / driving unit 250 is slight, so that the current command value = the motor current. Furthermore, the vehicle speed V is assumed to be constant.

  First, the effect of steering intervention compensation will be described.

  The steering angle command value θref was fixed at 0 [deg], and a simulation of automatic steering was performed when the driver's target angle θarm was input. As a reference, FIG. 25 shows the time response of the actual steering angle θr and the steering torque Tt with respect to the time change of the target angle θarm of the driver in the simulation considering the driver's steering model under the same conditions. In FIG. 25, the vertical axis represents the angle [deg] and the steering torque [Nm], the horizontal axis represents the time [sec], the thick solid line represents the driver's target angle θarm, and the thin solid line represents the actual steering angle (in this embodiment, the steering wheel). (Steering angle) θr, the broken line indicates the steering torque Tt. In FIG. 25, the assist control output gradual change gain Gft1 is 0%, that is, the assist control is disabled. FIG. 25 is an example of a simulation for explaining how the actual steering angle θr and the steering torque Tt change with respect to the change in the target angle θarm of the driver.

  With respect to changes in the actual steering angle θr and the steering torque Tt when the target angle θarm of the driver is input, there is a case where speed control is performed by PI control without steering intervention compensation and a case where there is steering intervention compensation. A comparison was made. In the former case, for comparison with the present embodiment, the assist control output gradual change gain Gft1 and the assist map gradual change gain Gft2 are both set to 100%. In the latter, the assist control output gradual change gain Gft1 is set to 0%. In the conventional prior art (for example, Patent Document 1), the assist control command value is 0 [A] during the steering angle control before switching, but it is estimated that steering intervention is more difficult than in the former case. So I omitted it.

  FIG. 26 shows the simulation result. The vertical axis represents the steering torque [Nm], the horizontal axis represents the actual steering angle [deg], and the case where there is no steering intervention compensation is indicated by a broken line, and the case where there is steering intervention compensation is indicated by a solid line. However, in the basic map unit 351 of the steering intervention compensation unit 350, the basic map is a straight line from the origin.

  As shown by the broken line in FIG. 26, when there is no steering intervention compensation, the actual steering angle θr is cut up to 7.5 [deg]. However, due to the influence of the PI control integration in the speed control, the speed deviation ( The deviation of the steering angular velocity command value and the actual steering angular velocity) continues to be accumulated, so that the steering angular command value θref (= 0 [deg]) is finally returned to a forcible value, and further 15 [Nm] or more. A very large steering torque is generated, which makes it difficult for the driver to steer.

  On the other hand, as shown by the solid line in FIG. 26, when there is steering intervention compensation, the steering can be made up to about 22 [deg], and the steering angle command value θref (= 0 [deg]) is pulled back. Nor. This is because the steering angular velocity command value ωref2 output from the steering intervention compensation unit 350 is added to the steering angular velocity command value ωref1 output from the position control unit 340, and the steering angular velocity command value ωref and the actual steering angular velocity ωr in the steered state are added. This is because the speed deviation is balanced near zero. Thus, the steering intervention by the driver can be realized by the function of the steering intervention compensation unit 350. Further, by increasing the gain of the output from the steering intervention compensation unit 350, lighter steering can be realized.

  Next, there is no steering intervention by the driver (steering hand input torque Th = 0 [Nm]), steering intervention compensation is not performed, and steering vibration during steering angle control in automatic steering when only steering angle control is executed. The effect on will be described.

  Prior to the description of the effect on the steering wheel vibration, in order to explain how the actual steering angle θr follows the steering angle command value θref, the following ability to the steering angle command value θref will be described.

  FIG. 27 shows an example of a time response in which the steering angle command value θref is changed in a ramp shape from 0 [deg] to 100 [deg]. In FIG. 27, the vertical axis represents the steering angle [deg], the horizontal axis represents the time [sec], and the dotted line represents the steering angle command value θref. The response of the target steering angle θt and the actual steering angle θr output from the steering wheel vibration removal unit 330 having a primary LPF with a cutoff frequency of 2 Hz to the steering angle command value θref is shown by a thin solid line and a thick line, respectively. Shown in solid line. FIG. 27 shows that the target steering angle θt and the actual steering angle θr follow the steering angle command value θref.

  From the above description, it can be said that both steering intervention and steering angle tracking can be realized during automatic steering.

  In the simulation for confirming the effect on the steering wheel vibration, when the steering angle control is performed with respect to the steering angle command value θref similar to FIG. 27, the time response of the torsion bar torque depending on the presence / absence of the steering wheel vibration removing unit 330 and the steering wheel damping unit 380 I investigated the difference. The handle vibration removing unit 330 uses a primary LPF having a cutoff frequency of 2 Hz. The handle damping unit 380 is a first-order filter that uses a gain Kv that provides a column axis equivalent torque of 10 Nm for a torsion bar torque of 1 Nm, a numerator cutoff frequency of 10 Hz, and a denominator cutoff frequency of 20 Hz. Phase lead compensation was performed. The result is shown in FIG. In FIG. 28, the vertical axis is the torsion bar torque [Nm], the horizontal axis is the time [sec], the solid line is the case where there is a vibration countermeasure by the handle vibration removing unit 330 and the handle vibration damping unit 380, and the dotted line is the vibration countermeasure. This is the case. It can be seen from FIG. 28 that the handle vibration is suppressed by the handle vibration removing unit 330 and the handle damping unit 380.

  Next, the effect of preventing a sudden change in the steering angle in the hand-off after the steering intervention (in a state where the steering intervention compensation is functioned) due to the restriction by the position control output variable restriction unit with respect to the steering angular velocity command value will be described.

  In a state where the target steering angle θt is fixed to 0 [deg], a simulation was performed in the case where there was steering intervention by the driver and the steering wheel was released after that. In the simulation, the set value A used in the position control output variable limiting unit is set to 1000 [deg / s], and the set value B is set to 100 [deg / s].

  FIG. 29 is a diagram illustrating an example of a time change of the driver's target angle θarm and an example of a time response of the steering wheel input torque Th as a response, and the vertical axis indicates the target angle θarm [deg] and the steering wheel input. Torque Th [Nm], the horizontal axis is time [sec], the thick solid line indicates the target angle θarm, and the thin solid line indicates the handle manual input torque Th. In the simulation, assuming that the steering wheel is released at a timing 3 [sec] after the start, the steering wheel manual input torque Th = 0 [Nm] is forcibly set at a timing 3 [sec]. Therefore, the steering wheel input torque Th is affected by the target angle θarm of the driver up to 3 [sec], but is not affected after 3 [sec]. In the simulation, the switching signal SW is in the “steering angle control mode”, and in the situation where the steering state is “automatic steering 1”, the determination of the manual input is “manual input” at the timing after 1.25 [sec] from the start. Assuming that the steering state is “automatic steering 2”, the limit value of the position control output variable limiting unit is changed from the set value A of 1000 [deg / s] to the set value B of 100 [deg / s]. To 0.25 [sec]. FIG. 30 is a diagram showing the time change of the limit value of the position control output variable limiter in that case. The limit value is changed in a ramp shape from 1.25 [sec] to 1.5 [sec]. ing. When the steering state becomes “automatic steering 1” by releasing the handle, the limit value is originally shifted to the set value A of 1000 [deg / s]. In order to show the effect of preventing sudden changes in an easy-to-understand manner, no transition is made.

  In order to see the effect of setting the limit value of the position control output variable limiter according to the steering state, the limit value is changed (the limit value is variable) and not (the limit value is constant). The time change of the steering angle θh according to whether or not the damper gain map is used in the steering intervention compensation unit was compared. FIG. 31 shows the simulation result. The vertical axis is the steering angle θh [deg], the horizontal axis is the time [sec], the limit value is constant and the damper gain map is not shown with a thin solid line, and the limit value is variable and the damper gain map is not shown with a broken line The case where the limit value is variable and the damper gain map is provided is indicated by a thick solid line. As can be seen from FIG. 31, in the thin solid line, the steering angle θh suddenly changes immediately after 3 [sec] when the steering wheel is released, and the target steering angle θt = 0 [deg] is overshot and converged. In the broken line, as compared with the thin solid line, the steering angle θh changes gently toward the target steering angle θt and converges with little overshoot. In the thick solid line, the steering wheel steering angle θh converges most gently on the target steering angle θt. In this way, it is possible to prevent a sudden change in the steering angle of the steering wheel by appropriately limiting the steering angular speed command value that is input to the steering angular speed control unit after releasing the steering wheel, and use a damper gain map for steering intervention compensation. By doing so, the effect can be improved.

  At the end of the explanation of the effect, there is a problem that the integral value of the I control is excessively accumulated due to the increase of the steering angular speed at the start of the steering angle control, and the steering angle control command value may become excessive (the problem in Patent Document 3 etc. ) Will be described.

  FIG. 32 is a diagram showing a change over time of the limit value in the target rudder angular velocity ωt, gradual gain, and speed command value variable limiting unit 360 when shifting from the manual steering state to the automatic steering state. Note that FIG. 32 shows only Gfa1 assuming that the speed control gradual change gain Gfa2 and the speed command gradual change gain Gfa3 change in synchronization with the steering angle control output gradual change gain Gfa1. Assuming that the assist control output gradual change gain Gft1 and the assist map gradual change gain Gft2 also change in synchronization with Gfa1, only the change in Gft1 is shown for reference. In addition, the magnitude of the limit value in the speed command value variable limiter 360 is set to be a small value when Gfa3 is less than a predetermined threshold, and gradually increases when Gfa3 is equal to or greater than the predetermined threshold.

  The steering angular speed command value ωref is multiplied by the speed command gradual change gain Gfa3 and further limited by the speed command value variable limiting unit 360 to become the target steering angular speed ωt. When the transition from the manual steering state to the automatic steering state starts, Gfa3 gradually increases from 0, and the target rudder angular velocity ωt also gradually increases from 0. After that, when the steering angular speed command value ωrefg, which is an input to the speed command value variable limiting unit 360, reaches the limit value (limit value a) at time t10, the target steering angular speed ωt becomes constant at the limit value a, but Gfa3 is Keeps increasing. When Gfa3 becomes a predetermined threshold at time t11, the limit value gradually increases, and the target rudder angular velocity ωt increases accordingly. When Gfa3 becomes 100% at time t12, and when the limit value reaches the limit value b at time t13, the target steering angular speed ωt changes within the limit value b. Since the target rudder angular speed ωt is limited by the limit value a between time points t10 and t13, and further limited by multiplication of the speed control gradual change gain Gfa2 in the rudder angular speed control unit 370, the steering angular speed control unit 370 Excessive accumulation of integral values is suppressed, and the current command value as the steering angle control output that causes the driver to feel uncomfortable can be reduced. Further, after the transition of the limit value is completed (that is, after time t13), the steering angular speed command value ωref is not limited by Gfa3 and the speed command value variable limiting unit 360, and the signal in the steering angular speed control unit 370 is not limited by Gfa2. Therefore, it is possible to shift to normal steering angle control.

  In addition, regarding the multiplication of each gradual gain (Gfa1 to Gfa4, Gft1, Gft2) in the first embodiment, when the cost is more important than the effect of the gradual gain multiplication, at least one multiplication is left and the subsequent multiplication is performed. Can be omitted. Also, each limiting unit (steering angle command value variable limiting unit, variable rate limiting unit, position control output variable limiting unit, speed command value variable limiting unit, steering angle control current command value limiting unit) is also omitted in the same case. Is possible. When the steering angle command value variable limiting unit 310, the variable rate limiting unit 320, the multiplication unit 391, and the steering wheel vibration removing unit 330 are omitted, the steering angle command value θref is input to the position control unit 340 as the target steering angle θt. Will be. When the multiplication unit 392 and the speed command value variable limiting unit 360 are omitted, the steering angular speed command value ωref is input to the steering angular speed control unit 370 as the target steering angular speed ωt.

  In the steering intervention compensation unit 350, the LPF 352B can be omitted. Further, a speed command value phase compensation unit 356 that performs phase compensation may be inserted before or after the basic map unit 351. That is, the configuration of the region R surrounded by the broken line in FIG. 11 may be configured as shown in FIG. 33 (A) or (B). The speed command value phase compensation unit 356 sets phase lead compensation as phase compensation. For example, phase lead compensation is performed with a primary filter having a numerator cutoff frequency of 1.0 Hz and a denominator cutoff frequency of 1.3 Hz. Do. Thereby, a refreshing feel can be realized.

  Another embodiment of the present invention will be described.

  In the first embodiment, the multiplication of the speed control gradual change gain Gfa2 in the rudder angular speed control unit 370 is performed on the control amount Ir1 that is the output from the integration unit 373, but with the output from the subtraction unit 375. It is also possible to carry out with respect to a certain steering angle control current command value IrefW.

  FIG. 34 is a configuration example (second embodiment) of the steering angular speed control unit in the case where the steering control current command value IrefW is multiplied by the speed control gradual change gain Gfa2. Compared with the rudder angular velocity control unit 370 in the first embodiment shown in FIG. 15, in the rudder angular velocity control unit 470 in the second embodiment, the multiplication unit 376 is not after the integration unit 373 but after the subtraction unit 375. The other configurations are the same.

  In the operation example of the second embodiment, in the operation example of the first embodiment shown in FIGS. 21 and 22, the same operation is performed until step S920 in which the integration unit 373 integrates the operation amount D1 to calculate the control amount Ir1. Thereafter, the control amount Ir1 is input to the subtraction unit 375, and the subtraction unit 375 calculates the control amount Ir3 ′ as a deviation (Ir1−Ir2) between the control amounts Ir1 and Ir2. Then, the multiplication unit 376 multiplies the control amount Ir3 ′ by the speed control gradual change gain Gfa2, and outputs the multiplication result to the addition unit 394 as the steering angle control current command value IrefW. After that (step S960), the operation is the same as that of the first embodiment.

  The multiplication of the speed control gradual change gain Gfa2 can be performed at other points in the steering angular speed control unit 370.

  In the configuration example (third embodiment) of the rudder angular speed control unit shown in FIG. 35, the deviation ωe that is the output from the subtraction unit 374 is multiplied by the speed control gradual change gain Gfa2. Compared with the steering angular velocity control unit 370 in the first embodiment shown in FIG. 15, in the steering angular velocity control unit 570 in the third embodiment, the multiplication unit 376 is not after the integration unit 373 but after the subtraction unit 374. The other configurations are the same.

  The operation example of the third embodiment is the same as the operation example of the first embodiment shown in FIGS. 21 and 22 until step S900 in which the subtraction unit 374 calculates the deviation ωe between the target steering angular velocity ωt and the actual steering angular velocity ωr. In operation, the deviation ωe is input not to the gain multiplication unit 371 but to the multiplication unit 376. The multiplication unit 376 multiplies the deviation ωe by the speed control gradual change gain Gfa2, and outputs the result to the gain multiplication unit 371 as the deviation ωe1. Thereafter, the operation is the same as that of the first embodiment except that step S930 is eliminated.

  In the above-described embodiments (first to third embodiments), the speed command value variable limiting unit 360 sets a limit value according to the speed command gradual change gain Gfa3, and the limit is set when Gfa3 reaches a predetermined threshold. Although the value is switched, the steering angle control output gradual change gain Gfa1 may be used instead of Gfa3, and the limit value may be switched when Gfa1 reaches 100%. In the configuration in this case (fourth embodiment), Gfa1 is input instead of Gfa3 to the speed command value variable limiting unit, and other configurations are the same as those in the other embodiments. In the operation of the fourth embodiment, the limit value determination determination operation (step S860 in FIG. 22) in the speed command value variable limiting unit is merely changed to checking whether Gfa1 is less than 100%. In the fourth embodiment, the change over time of the limit value in the target rudder angular velocity ωt, gradual gain, and speed command value variable limiting unit when shifting from the manual steering state to the automatic steering state is as shown in FIG. . Compared to the time change shown in FIG. 32, the limit value in the speed command value variable limiter gradually increases from time t12 when Gfa1 becomes 100%, and the target steering angular speed ωt also increases accordingly. Yes.

1 Handle 2 Column shaft (steering shaft, handle shaft)
DESCRIPTION OF SYMBOLS 10 Torque sensor 12 Vehicle speed sensor 13 Battery 20 Motor 21 Rotation angle sensor 30 Control unit (ECU)
31 Current command value calculating unit 33 Current limiting unit 34 Compensation signal generating unit 35 PI control unit 36 PWM control unit 37 Inverter 38 Motor current detector 100 Vehicle side ECU
110 vehicle state quantity detection unit 120 switching command unit 130 target trajectory calculation unit 140 vehicle motion control unit 141 rudder angle command value generation unit 200 EPS side ECU
210 EPS state quantity detection unit 220 switching determination / gradual change gain generation unit 221 switching determination unit 222 gradual gain generation unit 223 manual input determination unit 223A, 223B determination unit 224 steering state determination unit 225A, 225B, 225C, 225D smoothing filter Unit 226A, 226B, 226C, 226D Absolute value conversion unit 227A, 227B Determination processing unit 228 Steering angle control model unit 230 Assist control unit 240 Switching unit 250 Current control / drive unit 300 Steering angle control unit 310 Steering angle command value variable limiting unit 320 Variable rate limiting unit 330 Steering wheel vibration removing unit 340 Position control unit 341 Proportional gain unit 345 Position control output variable limiting unit 350 Steering intervention compensation unit 351 Basic map unit 352 Steering angular velocity calculation unit 353 Damper gain unit 356 Speed command value phase compensation unit 360 Speed command value variable limiter 370 470,570 steering angular velocity controller 371, 372 gain multiplication unit 373 integrating unit 380 handles the damping unit 381 gain section 382 damping the phase compensation unit 390 steering angle control current command value limiting section 400 plants

Claims (22)

In an electric power steering device that drives a motor based on a current command value and performs assist control and steering angle control on a steering system by drive control of the motor,
A steering angle control unit that calculates a steering angle control current command value for the steering angle control based on at least the steering angle command value and the actual steering angle;
A switching determination / gradual change gain generation unit that determines a steering state based on a determination of manual input and switches the steering state;
The switching determination / gradual gain generating unit is
A manual input determination unit including a first determination unit configured to determine the manual input using an error threshold with respect to an error between the estimated steering angle estimated based on the steering angle command value and the actual steering angle;
An electric power steering apparatus characterized in that the current command value is calculated using at least the steering angle control current command value. The first determination unit;
A plurality of error smoothing filters having different characteristics, each of the error smoothing filters smoothes the error to obtain a plurality of smoothing errors, and the error threshold is used for each of the smoothing errors. The electric power steering apparatus according to claim 1, wherein the manual input is determined. The first determination unit;
The electric power steering apparatus according to claim 2, wherein a plurality of error thresholds are used for at least one of the smoothing errors, and a plurality of determination results are provided as determination results with manual input. The manual input determination unit is
4. The electric power steering apparatus according to claim 1, further comprising a second determination unit configured to determine the manual input using a torque threshold with respect to the steering torque. 5. The second determination unit is
A plurality of torque smoothing filters having different characteristics, each of the torque smoothing filters smoothes the steering torque to obtain a plurality of smoothed steering torques, and the torque threshold value for each of the smoothed steering torques The electric power steering apparatus according to claim 4, wherein determination of the manual input is performed using a power. The second determination unit is
6. The electric power steering apparatus according to claim 5, wherein a plurality of torque threshold values are used for at least one smoothed steering torque, and a plurality of determination results are obtained as determination results with manual input. The rudder angle control unit
A position controller that calculates a steering angular velocity command value based on the steering angle command value and the actual steering angle;
A position control output variable limiting unit that limits the steering angular speed command value with a limit value 1 set according to the steering state, and outputs a limited steering angular speed command value;
The electric power steering apparatus according to claim 6, further comprising: a steering angular speed control unit that calculates the steering angular control current command value based on the limited steering angular speed command value and the actual steering angular speed. The rudder angle control unit
A steering intervention compensation unit for obtaining a compensation steering angular velocity command value for steering intervention compensation according to the steering torque, rotational speed information, and vehicle speed;
Compensate the limit steering angular velocity command value using the compensated steering angular velocity command value,
The steering intervention compensation unit
A basic map unit that obtains a first speed command value from the steering torque using a basic map that is vehicle speed sensitive, and a damper that obtains a second speed command value based on the rotational speed information using a damper gain map that is vehicle speed sensitive The electric power steering apparatus according to claim 7, further comprising a calculation unit, wherein the compensation steering angular speed command value is calculated from the first speed command value and the second speed command value.   The electric power steering apparatus according to claim 8, wherein the damper gain map has a characteristic that the damper gain also increases as the vehicle speed increases. The steering intervention compensation unit
A speed command value phase compensator for performing phase compensation is further provided in the former stage or the latter stage of the basic map part,
The electric power steering apparatus according to claim 8 or 9, wherein the first speed command value is obtained from the steering torque via the basic map unit and the speed command value phase compensation unit. The position controller is
The electric power steering device according to any one of claims 7 to 10, further comprising a proportional gain unit that calculates a rudder angular velocity command value by multiplying a deviation between the rudder angle command value and the actual steering angle by a proportional gain.   The electric power according to any one of claims 7 to 11, wherein the rudder angular speed control unit calculates the rudder angle control current command value by IP control using the limited rudder angular speed command value and the actual rudder angular speed. Steering device. The switching determination / gradual gain generating unit is
A steering state determination unit that determines the steering state based on a switching signal for switching the operation mode to the assist control mode or the steering angle control mode, the first determination result of the first determination unit, and the second determination result of the second determination unit. When,
The electric power steering apparatus according to claim 7, further comprising: a gradually changing gain generating unit that generates a gradually changing gain that adjusts the control amount of the assist control and the control amount of the steering angle control according to the steering state. The steering state determination unit is
When the switching signal is in the assist control mode,
Alternatively, when the immediately preceding steering state is automatic steering 1 or automatic steering 2 and the first determination result or the second determination result is manual input 3,
The electric power steering apparatus according to claim 13, wherein the steering state is determined as manual steering. The steering state determination unit is
When the immediately preceding steering state is the manual steering or the automatic steering 2, the switching signal is the steering angle control mode, and the first determination result and the second determination result are not manually input,
The electric power steering apparatus according to claim 14, wherein the steering state is determined as the automatic steering 1. The gradual gain generating unit
A predetermined first gain value for the automatic steering 1 is set to the gradual gain, a predetermined second gain value for the manual steering is set to the gradual gain,
When the steering state changes to the automatic steering 1, the gradual gain is changed to the first gain value, and when the steering state changes to the manual steering, the gradual gain is changed to the second gain value. The electric power steering apparatus according to claim 14 or 15, wherein the electric power steering apparatus is transited. The position control output variable limiting unit,
The electric power steering apparatus according to any one of claims 14 to 16, wherein when the steering state changes from the automatic steering 1 to the automatic steering 2 or the manual steering, the limit value 1 is shifted to a set value 1. The position control output variable limiting unit,
The electric power steering apparatus according to claim 17, wherein when the steering state changes from other than the automatic steering 1 to the automatic steering 1, the limit value 1 is changed to a setting value 2 larger than the setting value 1. The rudder angle control unit
The electric power steering according to any one of claims 14 to 18, further comprising a variable rate limiting unit that limits a change amount of the steering angle command value by a limit value 2 set according to the steering state. apparatus. The variable rate limiting unit is
The electric power steering apparatus according to claim 19, wherein when the steering state is changed from the automatic steering 1 to the automatic steering 2 or the manual steering, the limit value 2 is shifted to zero. The variable rate limiting unit is
21. The electric power steering apparatus according to claim 19 or 20, wherein when the steering state changes from other than the automatic steering 1 to the automatic steering 1, the limit value 2 is changed to a predetermined value. An assist control unit that calculates an assist control current command value for the assist control based on at least a steering torque;
The electric power steering apparatus according to claim 1, wherein the current command value is calculated from the assist control current command value and the steering angle control current command value.